First they brought boat noodles into the Melbourne mainstream; now the Soi 38 team are putting southern Thai flavours in the spotlight at their second restaurant, a bright and folksy eatery in the heart of the city.

Where Soi tried to replicate eating on the streets of Bangkok, right down to its car park location, R.Harn is a snapshot of the southern Thai food that co-owner Tang Piyaphanee grew up with.

The region’s sunshine-coloured dishes, pungent stink bean, and sweet-sour fish curries are rarely seen in Melbourne’s Thai restaurants. But R.Harn will boost the profile of Thailand’s coastal cooking, joining a buzzing local scene that now includes northern Isan-style restaurants, Thai barbecue, hot pot and more.

For Top Piyaphanee, the no-bookings venue is all about sharing the thrill of his first taste of southern Thai food – layered with spices, colour and sourness – when he met his wife.

“It’s got Malaysian, Singapore, Indian influences,” explains Top, who grew up in Bangkok and founded Soi 38 a decade ago. “But it’s the Thai version, so it’s intense!”

As well as serving a totally different cuisine, R.Harn feels nothing like Soi. Green timber wainscoting, floral patterns and mismatched chairs give the brand-new building a homely, feminine feel that’s matched by the design of the menu.

The long dinner menu is full of complementary dishes to be eaten banquet-style. There’s whole deep-fried pomfret, stir-fried cabbage with plump dried shrimp sourced especially from Thailand, and aromatic soups. Curries are a focus, with six choices ranging from “really intense” to “really light, but all of them emphasise fresh seafood”, says Top.

The shorter lunch menu is geared to quick solo visits, with complete meals. Khao yum, a rice salad described by Top as a “gateway dish” to the pungent flavours of southern Thai food, is powered by house-made fish sauce. The rice noodle dish kanom jeen is served here with two different curries – sour fish and sweet prawn – for guests to mix and match the contrasting flavours.

A liquor licence is on the way, but for now you can get Thai milk tea and thirst-quenchers like a lime drink with butterfly pea flower extract.

The Piyaphanees are committed to doing things the way they are back home. Mango sticky rice uses mahachanok mangoes, a Thai variety grown in Darwin; and fish sauce is being made in-house to a family recipe.

It’s not just a labour of love for the couple; the whole family is involved. Tang’s mother is sourcing ingredients such as shrimp paste from Chumphon province in the south of Thailand, while Top’s mum was charged with sourcing cutlery and the serving plates that cover two walls. Each brightly patterned plate has come from a family in her neighbourhood, who use them for Lunar New Year celebrations honouring ancestors.

“At least she’s stopped using TikTok all day,” laughs Top.

Open daily 11am-3pm, 5pm-9.30pm

264 La Trobe Street, Melbourne, instagram.com/r.harn